function newImage(arg) {
          if (document.images) {
              rslt = new Image();
              rslt.src = arg;
              return rslt;
          }
      }

      function changeImages() {
          if (document.images && (preloadFlag == true)) {
              for (var i=0; i<changeImages.arguments.length; i+=2) {
                  document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
              }
          }
      }

      var preloadFlag = false;
      function preloadImages() {
          if (document.images) {
              //menu_hyperthermia = newImage("img/menu_hyperthermia_layer.jpg");
			 menu_tour_over = newImage("/img/menu_tour-over.gif");
			menu_centers_over = newImage("/img/menu_centers-over.gif");
		menu_faqs_over = newImage("/img/menu_faqs-over.gif");
		menu_news_over = newImage("/img/menu_news-over.gif");
		menu_hyperthermia_over = newImage("/img/menu_hyperthermia-over.gif");
		menu_studies_over = newImage("/img/menu_studies-over.gif");
		menu_membership_over = newImage("/img/menu_membership-over.gif");
		menu_bublications_over = newImage("/img/menu_bublications-over.gif");
		menu_partners_over = newImage("/img/menu_partners-over.gif");
              preloadFlag = true;
          }
      }
	  

      function getLayer(name) {
      //gibt fuer jeden Browser die korrekte Layersyntax zurueck
        if (document.layers){
          return(document.layers[name]);
        }
        else if (document.all) {
          layer = eval('document.all.' + name + '.style');
          return(layer);
        }
        else if (document.getElementById && !document.all){
          layer = eval('document.getElementById(name).style');
          return(layer);
        }
        else{
          return(null);
        }
      }

      function setLayerVis(name, status) {
        if (preloadFlag == true) {
          getLayer(name).visibility = status;
		  
        }
        else {
          return;
        }
      }

      function showLayer ( layer ) {
        if( typeof( close_timer ) != 'undefined' && close_timer && getLayer(layer).visibility != 'hidden' && getLayer(layer).visibility != 'hide' ) {
            clearTimeout( close_timer );
        }
        setLayerVis (layer, "visible");

      }

      function startCloseTimer ( layer ) {
        close_timer = window.setTimeout('setLayerVis ("'+layer+'", "hidden")', 20);
      }